Apparatus for the control of highway-crossing signals



Feb. 17,' 1931. I L. o. GRONDAHL 1,792,335

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Filed March 18,1930 INVENTOR; L ,O. Gronda Patented Feb. 17, 1931 x unrrao WSTATESPATENT OFFICE LABS O. GBONDAHL, OI PITTSBURGH, PENNSYLVANIA, ASS I IGNOBTO THE UNION SWITCH a SIGNAL COMPANY, OF BWISSVALE, PENNSYLVANIA, ACORPORATION 01' PENNSYLVANIA AIPARATUS FOR THE CONTROL OFHLGHWAYJJBOSSING SIGNALS Application filed March 1a, 1930. Serial 1%.436,841.

My invention relates to apparatus for the 5 trolling signals 0 thischaracter without the necessity for continuous track circuits. Inaccordance with one form of my invention, the necessity for trackcircuits is eliminated entirely. Iwill describe two forms of apparatusembodying my invention, and will t on polnt out the novel featuresthereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view showingoneform of apparatus embodying my invention, in which form the necessityfor track circuits is avoided. Fig. 2 is a view showing a modificationof the apparatus shown in Fig. 1 and also embodying my invention, butrequiring short isolated track sections for the control of the highwaycrossing signal.

Similar reference characters refer to similar parts in each of theviews.

Referring first to Fig. 1, the reference characters 1 and 1 designatethe track rails of a railway track A, which track is intersected by ahighway H. Located at the intersection of the railway track and thehighway is a highway crossing signal S, which as here shown, is in theform of an electric bell.

Located to the left of the highway H is a light sensitive cell G whichnormally re ceives light from a lamp L these elements being so disposedthat the supply of light to the cell C is discontinued when a train orcar passes between the elements. Preferably the lamp and the cell aredisposed on oppo site sides of the track at about the level of the axlesof a car, and are diagonally disposed with respect to the track, so thatthe supply of light to the cell C is continuously cut off during thepassage of a car. The cell C comprises an enclosing tube which is openat the end toward the track, in order to prevent the light sensitiveelement of this cell from being influenced by light otherthan that whichis received from the lamp L Similarly, the lamp L comprises an enclosingtube which is open at the end toward the track and the inner end ofwhich constitutes a reflector.

Other cells C C and C are dis osed along the track between the cell Cand t e highway "H, and are arranged to be normally supplied energizedrelays E and F, the former of which preferably comprises two windings 18and 19. V V1nd 1ng18 of relay E is provided with a stick circuit whichpasses from terminal B of a suitable source of current, through cell Cfront contact 8 of relay E, and winding 18 of this relay to terminal 0of the same source of current. This winding is also provided w th apick-up circuit which passes from terminal B, through the cell C frontcontact 12 of relay F, and winding 18 to terminal 0. Wlnding 19 of relayE is provided with a holdlng circuit which passes from terminal B,through front contact 9 of relay E, windmg 19 of this relay, and backcontact 13 of relay F to terminal 0.

Relay F is provided with a stick circuit which passes from terminal B,through cell C front contact 11 of relay F, and the windng of this relayto terminal 0. This circuit 15 provided with a branch around the cell C,which includes cell G so that relay F will become deenergized when andonly when both of the cells C and C are dark. These cells are placedclose enough to ether to insure that they will both be dar ened at thesame time by a passing train. The reason for providing two cells for thecontrol of relay F, is to prevent this relay from being deenergized by aperson walking along the track. Momentary darkening of the other cellswill not disarrange the apparatus.

A third relay G is provided with a circuit which includes cell C,whereby this relay is normally energized but becomes deenergized while atrain is passing the highway H. As-

sociatd with relay G is a normally deenergized slow-releasin relay Mprovided with a circuit which includes a back contact 1501: relay G. Itfollows that when a train passes highway H, relay M will becomeenergized while relay G is deenergized, whereupon after relay Gagain'becomes energized, the front contacts of rela M will remain closedfor a brief interval time.

Relay F is provided with a pick-up circuit which passes from terminal B,through the cells C and C in multiple, front contact 16 of relay G,front contact 17 of relay M, and the winding-of relay F to terminal O.

Another relay D is provided with a circuit which includes cell G andanother slow-releasing relay K is provided with a circuit which includesback contact 5 of relay D. Relay F is provided with a second pick-upcircuit which includes front contact 6 of relay D, and front contact 7of relay K in series.

The signal S is provided with a circuit which passes from terminal B,through back contact 10 of relay E, back contact 14 of relay F, and thesignal S to terminal 0. It follows that this signal will operate whenand only when both relays E and F'are deenergized. 77

The operation of the apparatus shown in Fig. 1,is as followsz y YNormally all of the relays except K and M are energized, so that thesignal S is inactive. While a train moving toward the right is passingthe cell C it will deenergize relay D, and this will energize relay K,but the operation of these relays has no effect on the rest of theapparatus. -When the train passes cell C it will reduce the current inboth the stick and the pick-up circuits for relay E to such'value thatthis relay will release. Then before the train loses its influence oncell C it will obscure cells C and C thereby reducing the current in thestick circuit-for relay F to such an amount that this relay, likewise,will release. Relay. F will then stay open, because both of its pickupcircuits are open, and relay E will stay open because its pick-upcircuit is open at contact 12 of relay F. Relays'E and F both beingopen, the signal S will operate to indicate that a train is approachingthe highway H. When the train passes the highway, it will d'eenergizerelay G, and this will energize relay M; then during the brief intervalof time in which contacts 16 and 17 of these relays are both closed, oneof the pick-up circuits for relay F will be closed, so that this relaywill again become'energized. The closing of contact 12 of relay F willclose the pick-up circuit for relay E, so that the latter relay will,likewise, become energized. The operation of the signal S will thereforebe discontinued, and the parts of the apparatus will be restored to theconditions in which they are shown'in the drawing.

{When a train moves in the other direction, that is, toward the left, itwill deenergize relay G when it passes the highway H, and this willenergize relay M, but this 0 eration of relays G and M will have no eect on the other parts of the ap aratus. When the train obscures bothcells a and C relay F will release, thereby closing the holding circuitfor winding 19 of relay E at back contact 13 of relay F. It follows thatwhen the train obscures cell CF, relay E will remain energized, becausethis holding circuit remains closed. Consequently, signal S will not beset into operation because its circuit will remain open at back contact10 of relayE. When the train passes cell C the second pick-up circuitfor relay F will become closed, so that this relay will becomeenergized, and all parts ,of' the apparatus will be restored to theconditions in which they are shown in the drawing.

Referring now to- Fig. 2, the apparatus shown in this view is the sameas that shown in Fig. 1, except that short insulated track sections aresubstituted for the light responsive cells for the control of relays D,E, F and G. Three short sections P P and P are located to the left ofthe highway H, and a fourth section P is located at the highway, thesesections being formed by insulated joints 2 in one of the rails 1. Eachsection is provided with a source of current connected across the rails1 and 1, this source being represented by the terminals B and O.

is connected across the rails at section I,

through front contact 8 of this relay and contact 12 of relay F inmultiple, so that relay E is provided as in Fig. 1 with a stick circuitand a pick-up circuit. The holding circuit for winding 19 of relay E isthe same as in Fig. 1. Relay F is connected across the rails at sectionP through its own front contact 11, so that this relay is provided witha stick'circuit as in Fig. 1. The two pick-up circuits for relay F are.the same as in Fig. 1, and the circuit for the control of signal S,

is, likewise the same as in Fig. 1. The operaducing the current in thestick and 1. In combination, a railway track intersected b a hi hway,two normally energized rela' s and F, a stick circuit for rclay incluing its own front contact, a pick-up circuit for relay E including afront contact of relay F, a holding circuit for relay E including itsown front contact and a back contact of relay F, a stick circuit forrelay F including its own front contact, a normall energized relay G, aslow-releasing relay controlled by a back contact of relay G, a pick-u pcircuit for relay F including front contacts of relays G and M inseries, means controlled by a train approaching said highway folr; re-

10 -u circuits for relay E to open this relEiy an for subsequentlyreducin the current in the stick circuit for relay E to open the samebefore relay E can close, means controlled by such train when it reachesthe highway for causing relay G to release, and a highway crossingsignal controlled by said relays E and F.

2. In combination, a railway track intersected b a highway, two normallyenergized relays lil and F, a stick circuit for relay E including itsown front contact, a pick-up circuit for relay E including a frontcontact of relay F, a holding circuit for relay E includin its own frontcontact and a back contact of relay F, a stick circuit for relay Fincludin its own front contact, a normally energized relay G, aslow-releasing relay M controlled by a back contact of relay G, apick-up circuit for relay F including front contacts of relays G and Min series, means controlled by a train approaching said highway; forreducing the current in the stick and pic -up circuits for relay E toopen this relay and for subsequently reducing the current in the stickcircuit for relay F to open the same before relay E can close, meanscontrolled by such train when it reaches the highway for causing relay Gto release, a normally energized relay D, a slow-releasing relay Kcontrolled by a back contact of relay D, a second pick-up circuit forrelay F including front contacts of relays D and K in series,

means controlled by retrain moving away from'said highway for causingrelay D to release after the train has passed the locations whereinrelays E and F are influenced, and a highway crossing signal controlledby said relays E and F.

3. In combination, a'railway track intersected by a highway, threesources of light disposed along the railway, three light responsivecells C C and C normally receiving light from said three sourcesrespectively but arranged to be successively obscured by a trainapproaching said highway, two relays E and F, a stick circuit for relayE including a front contact thereof and cell G a pick-up circuit forrelay E including cell C and a front contact of relay F, a holdingcircuit for relay E including a front contact thereof and a back contactof relay F, a stick circuit for relay F including a front contactthereof and cells C and Cfi in multiple, a fourth source of light and afourth light responsive ,cell C normally receiving light t ierefrom butobscured when a train is adj acent said highway, a relay G provided witha circuit including cell C, a slow-releasing relay M controlled by aback contact of relay G, a pick-up circuit for relay F including, frontcontacts of relays G and M in series, and a hi hway crossing signalcontrolled by relays li and F. I

4. In combination, a railway track intersected by 'ahighway, threesources of light disposed along the railway, three light responsivecells C, C and C normally receiving light from said three sourcesrespectively but arranged to be successively obsoured by a trainapproaching said highway, two relays E and F, a stick circuit for relayE including a front contact thereof and cell G a pick-upcircuit forrelay E including cell C and a front contact of relay F, a holdingcircuit for relay E including a front contact thereof and a back contactof relay F, a stick circuit for relay F includin a front contact thereofand cells C and in multiple, a fourth source of light and a fourth lightresponsive cell C normally receiving light therefrom but obscured when atrain is adjacent said highway, a relay G provided with a circuitincluding cell C, a. slow-releasing relay M controlled by a back contactof relay G, a pick-up circuit for relay F including front contacts ofrelays G and M in series, a fifth source of light and a fifth lightresponsive cell C arranged to be obscured by ,a train moving away fromthe highway after it has influenced cell G a relay D provided with acircuit including cell C, a slow-releasing relay K controlled by a backcontact of relay D, a second pick-up circuit for relay F including frontcontacts of relays D and K in series, and a highway crossing signalcontrolled by relays E and F.

5. In combination, a railway track intersected by a highway, said trackbeing provided with three short insulated sections P P and P arranged tobe bridged successively in the order named by a train approaching thehighway, and with a fourth section P located adjacent the highway, asource of current connected across the rails of each section, two relaysD and G connected across the rails of sections P and P respectively, arelay F having a winding connected across the rails of section P througha front contact of the relay itself, a relay E having a windingconnected across the rails of section P through apath which includes afront contact of the relay itself and a front contact of relay 'F inmultiple, a holding circuit for relay E including a front contactthereof, and a back contact of relay F, two slow-releasing relays K andM controlled by back contacts of relays D and G, respectively, twoshunts for thecircuit of relay F around the front contact thereof, oneof which shunts includes front contacts of rela s G and M in series andthe other of which mcludes front contacts of relays D and K in series,and a highway crossing signal controlled by said relays E and F.

6. In combination, a railway track intersected by a hi hway, twonormally energized relays E and i means controlled by a trainapproaching the highway for first deenergizing relay E and forsubsequently deenergizing relay F before its influence over relay Eceases, means for preventing relay E from becoming reenergized untilrelay F again becomes energize means controlled by such train when itreaches the highway for reenergizing relay F, means responsive to theprior deenergization of relay F when a train moves in the otherdirection for preventing relay E from being deenergized by such train,means controlled by a train moving last-mentioned direction forreenerglzing relay F after it has passed the points at which said relaysare influenced, andva highway crossing signal set into operation whenand only when relays E and F are both, deenergized.

In testimony whereof I afiix my signature.

LARS O. GRONDAHL.

in the a

